New saturable-core Fault Current Limiter topology with reduced core size

Installation of new generating units and increased penetration of distributed generators (DGs) in the power systems increase the total power transmitted in the power grid. In the case of a fault, the amount of power captured by a short circuit is enlarged, leading to higher peaks of the fault currents and, consequentially, to higher stresses to the power system components. Installations of fault current limiters (FCLs) are expected to prevent expensive upgrade and replacement of the components exposed to the over-stresses. Inductive FCL are particularly interesting due to their inherent reaction to a fault. However, some challenges are to be solved: excessive weight and induced over-voltage across the DC winding. The goal of this paper is to introduce a new configuration of the inductive FCL, where the amount of the required material has been reduced considerably and the induced over-voltage across the DC winding is decreased. Employment of one core per-phase instead of two reduces the amount of magnetic material. The core has three legs, where the middle leg is used as a shunt path for the AC flux. It enables a gap insertion in the AC magnetic circuit without influencing the DC magnetic circuit, i.e. amount of DC winding material. This means that a smaller core (less magnetic material) can be used for a same power level. The simulation results obtained from FCL models created in SaberDesigner are presented. They have been confirmed through the testing of the lab-scale prototype.